This invention relates to filled compositions of polymer of olefins. In one of its aspect, this invention relates to improving physical characteristics of polymer of olefins by the addition of fillers. In another aspect of the invention, it relates to the use of mixed mineral fillers in compositions with polymer of olefin. In still another aspect of the invention, it relates to the use of mica with at least one other mineral filler in compositions with polymer of olefin.
Automotive companies have shown an increased interest in filled polymers of olefins, particularly when fillers are used that produce a higher flexural modulus or produce a higher impact strength. It has long been known that fiberglass is useful in producing higher flexural modulus so that the performance of fiberglass filled polymer of olefin has become a standard against which other fillers are measured. Apparently, mica has emerged as a filler that provides not only a better flexural modulus but also improved impact strength in a composition with polymer of olefin. There is, however, a major drawback to the use of mica in that an inherent tan or brown color is produced in the composition which requires very high pigment loadings to mask and produce colors acceptable to the automotive industry. It has now been found that the addition of mica along with talc or a combination of talc and clay produces compositions having better flexural modulus than fiberglass and that the combination of mica, talc, and clay also provides a better impact strength, taking advantage of the fact that a combination of mica and clay in combination with polymer of olefin has exceptionally good impact strength. The combination of mica with talc and/or clay also provides a lighter color which is easier to mask than when mica is used alone and provides compositions that are less abrasive and easier to mold than fiberglass.
It is therefore an object of this invention to provide filled compositions of polymer of olefins that have improved flexural modulus and/or improved impact strength as compared to unfilled polymer of olefin. It is another object of this invention to provide a method for improving the flexural modulus and/or impact strength of polymers of olefins by adding specific fillers. It is still another object of this invention to provide filled polymers having good color, good physical properties, and that are less abrasive and easier to mold than polymers of olefins filled with fiberglass.
Other aspects, objects and the various advantages of this invention will become apparent upon reading the specification and the appended claims.